They are nice looking chickens, but they just look young to me and not mature, yet. As they mature, pullets start to fill out. Their body shape starts to change. They look less lean and fuller, rounder, for the breeds you have. I think they need to grow up a little more. When they get closer to the age when they're going to lay, their combs and wattles will change. They'll go from small and pink, to larger and red. They also start to squat when you pet them.
If you go over to the breed pages at
WWW.Feathersite.com, you can look at pictures of chickens of all ages. You can go to the page for each of the breeds you have. At the top of the page are the hens/roosters, in the middle are the pullets/cockerels and at the bottom are the chicks. That might help you get an eye for how they look at various ages and stages of development.
What have you been feeding them while you've had them? If they've mainly been eating a standard feed for their age, they should be fine. I have seen chickens whose development was delayed because they were being fed mostly corn. Their bodies just didn't have enough nutrients and protein to mature on schedule. Too many unbalanced treats or too much scratch can be a problem, too. If they've mainly been on a balanced feed, though, that shouldn't be an issue.
I think they're just not old enough to lay, yet.